The present invention relates to a feeding device for feeding fuel.
Feeding devices of the above mentioned general type are known in the art. In a known feeding device the fuel is supplied from a fuel tank, for example to an injection system of the internal combustion engine of a motor vehicle. Such a feeding device provided with a housing of synthetic plastic is disclosed for example in the German patent document DE 44 44 854 A1. In this feeding device, the feed pump is driven by an electric motor, and the fuel flows from the feed pump through a pre-filter, and after the feed pump is supplied under the feeding pressure to a main filter. These components are arranged in a filter casing with a removable cover. The electric motor and the feed pump are located in a central chamber, and the main filter is located in a ring chamber which is arranged concentrically around the main chamber.
The cover of the filter casing of this device has communications to tubular connections or pressure hoses through which the fuel is supplied to a connecting flange on the fuel tank. The feeding device forms a complete feeding module which can be directly mounted in the fuel tank. The fuel is aspirated from below on the feeding module and can be supplied from the connecting flange on the cover of the fuel tank through a supply conduit to an internal combustion engine.
Such a feeding module needs a plurality of connecting flanges and suspensions, for example for a fixed suspension of the central fuel pump. They are geometrically complicated and therefore produced of synthetic plastic, for example a synthetic plastic injection molded parts, for costs reasons. In this known device it is important to maintain a space for components which is as small as possible and to prevent electrical discharge which can lead to an ignition of the fuel or fuel-air mixture in the tank. The corresponding withdrawl of electrostatic charges can be performed with difficulties because the components are composed of synthetic plastic and they are either non conductive or have poor electrical conductivity.
Accordingly, its an object of present invention to provide a feeding device of the above mentioned general types which avoids the disadadvantages of the prior art.
In keeping with these objects and with others which will become apparent hereinafter, one feature of present invention resides, briefly stated, in a feeding device of the above mentioned type, in which a metal jacket is arranged in or on the concentric housing walls of the filter casing for receiving the filtering means at both sides of the filtering means or at one side.
When the feeding device is designed in accordance with the present invention, then in advantageous manner, a geometrical relatively complicated housing can be produced by free shaping of synthetic plastic, and with simple means an improvement of the strength properties is obtained with a small wall thickness, since the outer diameter of the filter casing can be maintained small due to relatively thin and eventually cast metal jacket. The synthetic plastic housing does not have any swelling problems under the action of the through flowing fuel which can lead to changes of its geometry.
Moreover, in the inventive device static discharges are withdrawn, since a metal jacket is arranged on the filtering means at the inner and/or outer side. This can be provided in a simple manner with an electrical connecting means.
Also, in advantageous manner uniform electrical potential can be produced through the metal jacket, for example through an electrically conductive tank cover, an electrically conductive feed pump, or a similar part of a motor vehicle located in a feeding path of the fuel.
In accordance with a preferable embodiment of the invention, the metal jacket can be formed as a tubular sleeve or a metal plate which is bent to form a tube. It can be interlocked or overlapped at the axial seam location.
Furthermore, the metal jacket can be provided with drilled openings or punched holes on its periphery, to ensure an efficient mechanical connection to the synthetic plastic parts of the filter casing. This advantage is also obtained when the metal jacket is provided at the side facing the filter unit with imprints, indentations and similar roughnesses.
The metal jacket, before the final mounting can extend substantially over the synthetic plastic part of the filtering unit, and then mounted by crimping, flanging, mortising on the housing part and on the cover for the filtering unit. Thereby a mechanical connection between these components can be established.
The metal jacket can be also produced on a terminal post of the electric motor for driving the fuel pump. Thereby a simple terminal guide for the electric motor is formed.
The novel features which are considered as characteristic for the present invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.